Method to animate a stroke along a curve
Add a Bezier Curve and set it to the required path using subdivide to add points as required. Click the green curve (1) on the properties panel and then the Geometry drop down (2).
In the Bevel section leave the type at Round then increase the Depth (3) slightly. Click to open Start &amp; End Mapping (4) and set both Factor Start and End to 0.
Go to the first frame in the timeline. Right-click on Factor Start and select 'Insert Keyframe'. The dot after the Factor Start entry (6) will change to a diamond shape.
Go to your required end frame on the timeline, set Frame Start to 1 and click the diamond to add a key frame. Run the animation.